1. Field of the Invention
The present invention relates to a golf club head durability of which has been improved by providing a crown-side thick-walled rib and a sole-side thick-walled rib on an inner surface of the head.
2. Description of the Background Art
In recent years have been proposed various golf club heads having a hollow structure including a face portion including a central thick-walled part with a large thickness and a peripheral thin-walled part with a small thickness which surrounds the central thick-walled part (see Japanese Patent Application Publication No. 2002-315854). Such a golf club head has an advantage that because of presence of the peripheral thin-walled part, reduction of resilience performance can be controlled even during a mishit in which a golf ball is hit at a position which is off a center of a face. However, such a face portion tends to have low durability at a boundary part between the central thick-walled part and the peripheral thin-walled part.
In order to prevent the drawback as described above, structure of the face portion in which a plurality of reinforcing ribs radially extends from the central thick-walled part is proposed (see Japanese Patent Application Publication No. 2003-290398 or Japanese Patent Application Publication No. 2009-247497). However, since any reinforcing ribs in these heads terminate within the face, there is further room for improvement in durability.